When a claim is denied or stalls, a written complaint is the tool that moves it. It has a set order, and most people lose ground by calling angrily first and writing later. Work through the steps in sequence and keep a file as you go.
Start with the decision in writing
If you only heard the denial or delay on the phone, ask for it in writing. Note the reason the company gave, the section of the contract it cited, and the date of the letter or call. Do not argue the decision yet. You need the exact wording before you can answer it.
Write a dated letter
Send a short letter that states what happened, what you expected under the contract, and what you want done. Quote the contract section by its title and page, not from memory. Keep a copy and send the letter in a way that leaves a record of delivery. Ask for a written reply by a stated date, and treat that date as the deadline you set, since the company will not set it for you.
Keep a call log
Each phone call gets its own entry: the date, the time, the name of the person you spoke to, the claim reference, and what was promised. Promises made on a call are hard to enforce unless they are repeated in writing, so follow every call with a short email or letter that restates what you were told.
Escalate to the regulator
If the reply is missing, unclear, or still a denial you cannot match to the contract, contact the state office that oversees the company's registration or the state consumer protection office. Bring the packet: the contract, the claim letters, the call log, and the repair invoices. Putting that packet in order is the work that matters most. This is general information about how complaints usually move, not legal advice. If the amount in dispute is large, a licensed attorney in your state can tell you what applies to your facts.